save state is no more

[l2tpns.git] / l2tpns.c

diff --git a/l2tpns.c b/l2tpns.c
index f49586b..a28cd5f 100644 (file)
--- a/l2tpns.c
+++ b/l2tpns.c
@@ -4,7 +4,7 @@
 // Copyright (c) 2002 FireBrick (Andrews & Arnold Ltd / Watchfront Ltd) - GPL licenced
 // vim: sw=8 ts=8
 
 // Copyright (c) 2002 FireBrick (Andrews & Arnold Ltd / Watchfront Ltd) - GPL licenced
 // vim: sw=8 ts=8
 

-char const *cvs_id_l2tpns = "$Id: l2tpns.c,v 1.82 2005/02/09 00:16:17 bodea Exp $";
+char const *cvs_id_l2tpns = "$Id: l2tpns.c,v 1.85 2005/03/10 03:08:08 bodea Exp $";

 
 #include <arpa/inet.h>
 #include <assert.h>
 
 #include <arpa/inet.h>
 #include <assert.h>


@@ -187,7 +187,7 @@ static int remove_plugin(char *plugin_name);
 static void plugins_done(void);
 static void processcontrol(uint8_t *buf, int len, struct sockaddr_in *addr, int alen);
 static tunnelidt new_tunnel(void);
 static void plugins_done(void);
 static void processcontrol(uint8_t *buf, int len, struct sockaddr_in *addr, int alen);
 static tunnelidt new_tunnel(void);

-static int unhide_avp(uint8_t *avp, tunnelidt t, sessionidt s, uint16_t length);
+static void unhide_value(uint8_t *value, size_t len, uint16_t type, uint8_t *vector, size_t vec_len);

 
 // return internal time (10ths since process startup)
 static clockt now(void)
 
 // return internal time (10ths since process startup)
 static clockt now(void)


@@ -660,7 +660,7 @@ sessionidt sessionbyip(in_addr_t ip)
        int s = lookup_ipmap(ip);
        CSTAT(sessionbyip);
 
        int s = lookup_ipmap(ip);
        CSTAT(sessionbyip);
 

-       if (s > 0 && s < MAXSESSION && session[s].tunnel)
+       if (s > 0 && s < MAXSESSION && session[s].opened)

                return (sessionidt) s;
 
        return 0;
                return (sessionidt) s;
 
        return 0;


@@ -679,7 +679,7 @@ sessionidt sessionbyipv6(struct in6_addr ip)
                s = lookup_ipv6map(ip);
        }
 
                s = lookup_ipv6map(ip);
        }
 

-       if (s > 0 && s < MAXSESSION && session[s].tunnel)
+       if (s > 0 && s < MAXSESSION && session[s].opened)

                return s;
 
        return 0;
                return s;
 
        return 0;


@@ -815,8 +815,11 @@ sessionidt sessionbyuser(char *username)
        int s;
        CSTAT(sessionbyuser);
 
        int s;
        CSTAT(sessionbyuser);
 

-       for (s = 1; s < MAXSESSION ; ++s)
+       for (s = 1; s <= config->cluster_highest_sessionid ; ++s)

        {
        {

+               if (!session[s].opened)
+                       continue;
+

                if (session[s].walled_garden)
                        continue;               // Skip walled garden users.
 
                if (session[s].walled_garden)
                        continue;               // Skip walled garden users.
 


@@ -858,17 +861,16 @@ void send_garp(in_addr_t ip)
        sendarp(ifr.ifr_ifindex, mac, ip);
 }
 
        sendarp(ifr.ifr_ifindex, mac, ip);
 }
 

-// Find session by username, 0 for not found

 static sessiont *sessiontbysessionidt(sessionidt s)
 {
 static sessiont *sessiontbysessionidt(sessionidt s)
 {

-       if (!s || s > MAXSESSION) return NULL;
+       if (!s || s >= MAXSESSION) return NULL;

        return &session[s];
 }
 
 static sessionidt sessionidtbysessiont(sessiont *s)
 {
        sessionidt val = s-session;
        return &session[s];
 }
 
 static sessionidt sessionidtbysessiont(sessiont *s)
 {
        sessionidt val = s-session;

-       if (s < session || val > MAXSESSION) return 0;
+       if (s < session || val >= MAXSESSION) return 0;

        return val;
 }
 
        return val;
 }
 


@@ -1357,7 +1359,7 @@ static void controladd(controlt * c, tunnelidt t, sessionidt s)
 //
 void throttle_session(sessionidt s, int rate_in, int rate_out)
 {
 //
 void throttle_session(sessionidt s, int rate_in, int rate_out)
 {

-       if (!session[s].tunnel)
+       if (!session[s].opened)

                return; // No-one home.
 
        if (!*session[s].user)
                return; // No-one home.
 
        if (!*session[s].user)


@@ -1395,7 +1397,7 @@ void throttle_session(sessionidt s, int rate_in, int rate_out)
 // add/remove filters from session (-1 = no change)
 static void filter_session(sessionidt s, int filter_in, int filter_out)
 {
 // add/remove filters from session (-1 = no change)
 static void filter_session(sessionidt s, int filter_in, int filter_out)
 {

-       if (!session[s].tunnel)
+       if (!session[s].opened)

                return; // No-one home.
 
        if (!*session[s].user)
                return; // No-one home.
 
        if (!*session[s].user)


@@ -1438,9 +1440,9 @@ void sessionshutdown(sessionidt s, char *reason)
 
        CSTAT(sessionshutdown);
 
 
        CSTAT(sessionshutdown);
 

-       if (!session[s].tunnel)
+       if (!session[s].opened)

        {
        {

-               LOG(3, s, session[s].tunnel, "Called sessionshutdown on a session with no tunnel.\n");
+               LOG(3, s, session[s].tunnel, "Called sessionshutdown on an unopened session.\n");

                return;                   // not a live session
        }
 
                return;                   // not a live session
        }
 


@@ -1451,7 +1453,7 @@ void sessionshutdown(sessionidt s, char *reason)
                run_plugins(PLUGIN_KILL_SESSION, &data);
        }
 
                run_plugins(PLUGIN_KILL_SESSION, &data);
        }
 

-       if (session[s].opened && !walled_garden && !session[s].die)
+       if (!walled_garden && !session[s].die)

        {
                // RADIUS Stop message
                uint16_t r = session[s].radius;
        {
                // RADIUS Stop message
                uint16_t r = session[s].radius;


@@ -1514,7 +1516,7 @@ void sessionshutdown(sessionidt s, char *reason)
        }
 
        if (!session[s].die)
        }
 
        if (!session[s].die)

-               session[s].die = now() + 150; // Clean up in 15 seconds
+               session[s].die = TIME + 150; // Clean up in 15 seconds

 
        // update filter refcounts
        if (session[s].filter_in) ip_filters[session[s].filter_in - 1].used--;
 
        // update filter refcounts
        if (session[s].filter_in) ip_filters[session[s].filter_in - 1].used--;


@@ -1589,12 +1591,21 @@ void sendipcp(tunnelidt t, sessionidt s)
 }
 
 // kill a session now
 }
 
 // kill a session now

-static void sessionkill(sessionidt s, char *reason)
+void sessionkill(sessionidt s, char *reason)

 {
 
        CSTAT(sessionkill);
 
 {
 
        CSTAT(sessionkill);
 

-       session[s].die = now();
+       if (!session[s].opened) // not alive
+               return;
+
+       if (session[s].next)
+       {
+               LOG(0, s, session[s].tunnel, "Tried to kill a session with next pointer set (%d)\n", session[s].next);
+               return;
+       }
+
+       session[s].die = TIME;

        sessionshutdown(s, reason);  // close radius/routes, etc.
        if (session[s].radius)
                radiusclear(session[s].radius, s); // cant send clean accounting data, session is killed
        sessionshutdown(s, reason);  // close radius/routes, etc.
        if (session[s].radius)
                radiusclear(session[s].radius, s); // cant send clean accounting data, session is killed


@@ -1636,7 +1647,7 @@ static void tunnelkill(tunnelidt t, char *reason)
                controlfree = c;
        }
        // kill sessions
                controlfree = c;
        }
        // kill sessions

-       for (s = 1; s < MAXSESSION; s++)
+       for (s = 1; s <= config->cluster_highest_sessionid ; ++s)

                if (session[s].tunnel == t)
                        sessionkill(s, reason);
 
                if (session[s].tunnel == t)
                        sessionkill(s, reason);
 


@@ -1663,12 +1674,12 @@ static void tunnelshutdown(tunnelidt t, char *reason)
        LOG(1, 0, t, "Shutting down tunnel %d (%s)\n", t, reason);
 
        // close session
        LOG(1, 0, t, "Shutting down tunnel %d (%s)\n", t, reason);
 
        // close session

-       for (s = 1; s < MAXSESSION; s++)
+       for (s = 1; s <= config->cluster_highest_sessionid ; ++s)

                if (session[s].tunnel == t)
                        sessionshutdown(s, reason);
 
        tunnel[t].state = TUNNELDIE;
                if (session[s].tunnel == t)
                        sessionshutdown(s, reason);
 
        tunnel[t].state = TUNNELDIE;

-       tunnel[t].die = now() + 700; // Clean up in 70 seconds
+       tunnel[t].die = TIME + 700; // Clean up in 70 seconds

        cluster_send_tunnel(t);
        // TBA - should we wait for sessions to stop?
        {                            // Send StopCCN
        cluster_send_tunnel(t);
        // TBA - should we wait for sessions to stop?
        {                            // Send StopCCN


@@ -1750,7 +1761,7 @@ void processudp(uint8_t * buf, int len, struct sockaddr_in *addr)
        {                          // control
                uint16_t message = 0xFFFF;      // message type
                uint8_t fatal = 0;
        {                          // control
                uint16_t message = 0xFFFF;      // message type
                uint8_t fatal = 0;

-               uint8_t mandatorymessage = 0;
+               uint8_t mandatory = 0;

                uint8_t chap = 0;               // if CHAP being used
                uint16_t asession = 0;          // assigned session
                uint32_t amagic = 0;            // magic number
                uint8_t chap = 0;               // if CHAP being used
                uint16_t asession = 0;          // assigned session
                uint32_t amagic = 0;            // magic number


@@ -1766,7 +1777,10 @@ void processudp(uint8_t * buf, int len, struct sockaddr_in *addr)
                        return;
                }
 
                        return;
                }
 

-               if ((*buf & 0xCA) != 0xC8)
+               // control messages must have bits 0x80|0x40|0x08
+               // (type, length and sequence) set, and bits 0x02|0x01
+               // (offset and priority) clear
+               if ((*buf & 0xCB) != 0xC8)

                {
                        LOG(1, s, t, "Bad control header %02X\n", *buf);
                        STAT(tunnel_rx_errors);
                {
                        LOG(1, s, t, "Bad control header %02X\n", *buf);
                        STAT(tunnel_rx_errors);


@@ -1877,23 +1891,42 @@ void processudp(uint8_t * buf, int len, struct sockaddr_in *addr)
                if (l)
                {                     // if not a null message
                        // process AVPs
                if (l)
                {                     // if not a null message
                        // process AVPs

-                       while (l && !(fatal & 0x80))
+                       while (l && !(fatal & 0x80)) // 0x80 = mandatory AVP

                        {
                                uint16_t n = (ntohs(*(uint16_t *) p) & 0x3FF);
                                uint8_t *b = p;
                                uint8_t flags = *p;
                                uint16_t mtype;
                        {
                                uint16_t n = (ntohs(*(uint16_t *) p) & 0x3FF);
                                uint8_t *b = p;
                                uint8_t flags = *p;
                                uint16_t mtype;

-                               p += n;       // next
-                               if (l < n)
+                               if (n > l)

                                {
                                        LOG(1, s, t, "Invalid length in AVP\n");
                                        STAT(tunnel_rx_errors);
                                {
                                        LOG(1, s, t, "Invalid length in AVP\n");
                                        STAT(tunnel_rx_errors);

-                                       fatal = flags;

                                        return;
                                }
                                        return;
                                }

+                               p += n;       // next

                                l -= n;
                                l -= n;

+                               if (flags & 0x3C) // reserved bits, should be clear
+                               {
+                                       LOG(1, s, t, "Unrecognised AVP flags %02X\n", *b);
+                                       fatal = flags;
+                                       continue; // next
+                               }
+                               b += 2;
+                               if (*(uint16_t *) (b))
+                               {
+                                       LOG(2, s, t, "Unknown AVP vendor %d\n", ntohs(*(uint16_t *) (b)));
+                                       fatal = flags;
+                                       continue; // next
+                               }
+                               b += 2;
+                               mtype = ntohs(*(uint16_t *) (b));
+                               b += 2;
+                               n -= 6;
+

                                if (flags & 0x40)
                                {
                                if (flags & 0x40)
                                {

+                                       uint16_t orig_len;
+

                                        // handle hidden AVPs
                                        if (!*config->l2tpsecret)
                                        {
                                        // handle hidden AVPs
                                        if (!*config->l2tpsecret)
                                        {


@@ -1907,40 +1940,36 @@ void processudp(uint8_t * buf, int len, struct sockaddr_in *addr)
                                                fatal = flags;
                                                continue;
                                        }
                                                fatal = flags;
                                                continue;
                                        }

+                                       if (n < 8)
+                                       {
+                                               LOG(2, s, t, "Short hidden AVP.\n");
+                                               fatal = flags;
+                                               continue;
+                                       }
+

                                        LOG(4, s, t, "Hidden AVP\n");
                                        LOG(4, s, t, "Hidden AVP\n");

+

                                        // Unhide the AVP
                                        // Unhide the AVP

-                                       n = unhide_avp(b, t, s, n);
-                                       if (n == 0)
+                                       unhide_value(b, n, mtype, session[s].random_vector, session[s].random_vector_length);
+
+                                       orig_len = ntohs(*(uint16_t *) b);
+                                       if (orig_len > n + 2)

                                        {
                                                fatal = flags;
                                                continue;
                                        }
                                        {
                                                fatal = flags;
                                                continue;
                                        }

+
+                                       b += 2;
+                                       n = orig_len;

                                }
                                }

-                               if (*b & 0x3C)
-                               {
-                                       LOG(1, s, t, "Unrecognised AVP flags %02X\n", *b);
-                                       fatal = flags;
-                                       continue; // next
-                               }
-                               b += 2;
-                               if (*(uint16_t *) (b))
-                               {
-                                       LOG(2, s, t, "Unknown AVP vendor %d\n", ntohs(*(uint16_t *) (b)));
-                                       fatal = flags;
-                                       continue; // next
-                               }
-                               b += 2;
-                               mtype = ntohs(*(uint16_t *) (b));
-                               b += 2;
-                               n -= 6;

 
                                LOG(4, s, t, "   AVP %d (%s) len %d\n", mtype, avp_name(mtype), n);
                                switch (mtype)
                                {
                                case 0:     // message type
                                        message = ntohs(*(uint16_t *) b);
 
                                LOG(4, s, t, "   AVP %d (%s) len %d\n", mtype, avp_name(mtype), n);
                                switch (mtype)
                                {
                                case 0:     // message type
                                        message = ntohs(*(uint16_t *) b);

+                                       mandatory = flags & 0x80;

                                        LOG(4, s, t, "   Message type = %d (%s)\n", *b, l2tp_message_type(message));
                                        LOG(4, s, t, "   Message type = %d (%s)\n", *b, l2tp_message_type(message));

-                                       mandatorymessage = flags;

                                        break;
                                case 1:     // result code
                                        {
                                        break;
                                case 1:     // result code
                                        {


@@ -2202,7 +2231,8 @@ void processudp(uint8_t * buf, int len, struct sockaddr_in *addr)
                                        if (!sessionfree)
                                        {
                                                STAT(session_overflow);
                                        if (!sessionfree)
                                        {
                                                STAT(session_overflow);

-                                               tunnelshutdown(t, "No free sessions");
+                                               LOG(1, 0, t, "No free sessions");
+                                               return;

                                        }
                                        else
                                        {
                                        }
                                        else
                                        {


@@ -2226,7 +2256,7 @@ void processudp(uint8_t * buf, int len, struct sockaddr_in *addr)
 
                                                c = controlnew(11); // sending ICRP
                                                session[s].id = sessionid++;
 
                                                c = controlnew(11); // sending ICRP
                                                session[s].id = sessionid++;

-                                               session[s].opened = time(NULL);
+                                               session[s].opened = time_now;

                                                session[s].tunnel = t;
                                                session[s].far = asession;
                                                session[s].last_packet = time_now;
                                                session[s].tunnel = t;
                                                session[s].far = asession;
                                                session[s].last_packet = time_now;


@@ -2264,8 +2294,8 @@ void processudp(uint8_t * buf, int len, struct sockaddr_in *addr)
                                        break;
                                default:
                                        STAT(tunnel_rx_errors);
                                        break;
                                default:
                                        STAT(tunnel_rx_errors);

-                                       if (mandatorymessage & 0x80)
-                                               tunnelshutdown(t, "Unknown message");
+                                       if (mandatory)
+                                               tunnelshutdown(t, "Unknown message type");

                                        else
                                                LOG(1, s, t, "Unknown message type %d\n", message);
                                        break;
                                        else
                                                LOG(1, s, t, "Unknown message type %d\n", message);
                                        break;


@@ -2306,7 +2336,7 @@ void processudp(uint8_t * buf, int len, struct sockaddr_in *addr)
                        l -= 2;
                }
 
                        l -= 2;
                }
 

-               if (s && !session[s].tunnel)    // Is something wrong??
+               if (s && !session[s].opened)    // Is something wrong??

                {
                        if (!config->cluster_iam_master)
                        {
                {
                        if (!config->cluster_iam_master)
                        {


@@ -2316,9 +2346,7 @@ void processudp(uint8_t * buf, int len, struct sockaddr_in *addr)
                        }
 
 
                        }
 
 

-                       LOG(1, s, t, "UDP packet contains session %d but no session[%d].tunnel "
-                                    "exists (LAC said tunnel = %d).  Dropping packet.\n", s, s, t);
-
+                       LOG(1, s, t, "UDP packet contains session which is not opened.  Dropping packet.\n");

                        STAT(tunnel_rx_errors);
                        return;
                }
                        STAT(tunnel_rx_errors);
                        return;
                }


@@ -2525,7 +2553,7 @@ static int regular_cleanups(void)
                if (s > config->cluster_highest_sessionid)
                        s = 1;
 
                if (s > config->cluster_highest_sessionid)
                        s = 1;
 

-               if (!session[s].tunnel) // Session isn't in use
+               if (!session[s].opened) // Session isn't in use

                        continue;
 
                if (!session[s].die && session[s].ip && !(session[s].flags & SF_IPCP_ACKED))
                        continue;
 
                if (!session[s].die && session[s].ip && !(session[s].flags & SF_IPCP_ACKED))


@@ -3134,7 +3162,7 @@ static void initdata(int optdebug, char *optconfig)
        memset(ip_address_pool, 0, sizeof(ippoolt) * MAXIPPOOL);
 
                // Put all the sessions on the free list marked as undefined.
        memset(ip_address_pool, 0, sizeof(ippoolt) * MAXIPPOOL);
 
                // Put all the sessions on the free list marked as undefined.

-       for (i = 1; i < MAXSESSION - 1; i++)
+       for (i = 1; i < MAXSESSION; i++)

        {
                session[i].next = i + 1;
                session[i].tunnel = T_UNDEF;    // mark it as not filled in.
        {
                session[i].next = i + 1;
                session[i].tunnel = T_UNDEF;    // mark it as not filled in.


@@ -3143,7 +3171,7 @@ static void initdata(int optdebug, char *optconfig)
        sessionfree = 1;
 
                // Mark all the tunnels as undefined (waiting to be filled in by a download).
        sessionfree = 1;
 
                // Mark all the tunnels as undefined (waiting to be filled in by a download).

-       for (i = 1; i < MAXTUNNEL- 1; i++)
+       for (i = 1; i < MAXTUNNEL; i++)

                tunnel[i].state = TUNNELUNDEF;  // mark it as not filled in.
 
        if (!*hostname)
                tunnel[i].state = TUNNELUNDEF;  // mark it as not filled in.
 
        if (!*hostname)


@@ -3269,8 +3297,9 @@ void rebuild_address_pool(void)
        for (i = 0; i < MAXSESSION; ++i)
        {
                int ipid;
        for (i = 0; i < MAXSESSION; ++i)
        {
                int ipid;

-               if (!session[i].ip || !session[i].tunnel)
+               if (!(session[i].opened && session[i].ip))

                        continue;
                        continue;

+

                ipid = - lookup_ipmap(htonl(session[i].ip));
 
                if (session[i].ip_pool_index < 0)
                ipid = - lookup_ipmap(htonl(session[i].ip));
 
                if (session[i].ip_pool_index < 0)


@@ -4016,7 +4045,7 @@ int sessionsetup(tunnelidt t, sessionidt s)
 
        LOG(3, s, t, "Doing session setup for session\n");
 
 
        LOG(3, s, t, "Doing session setup for session\n");
 

-       if (!session[s].ip || session[s].ip == 0xFFFFFFFE)
+       if (!session[s].ip)

        {
                assign_ip_address(s);
                if (!session[s].ip)
        {
                assign_ip_address(s);
                if (!session[s].ip)


@@ -4619,7 +4648,7 @@ void become_master(void)
        {
                for (s = 1; s <= config->cluster_highest_sessionid ; ++s)
                {
        {
                for (s = 1; s <= config->cluster_highest_sessionid ; ++s)
                {

-                       if (!session[s].tunnel) // Not an in-use session.
+                       if (!session[s].opened) // Not an in-use session.

                                continue;
 
                        run_plugins(PLUGIN_NEW_SESSION_MASTER, &session[s]);
                                continue;
 
                        run_plugins(PLUGIN_NEW_SESSION_MASTER, &session[s]);


@@ -4651,7 +4680,7 @@ int cmd_show_hist_idle(struct cli_def *cli, char *command, char **argv, int argc
        for (s = 1; s <= config->cluster_highest_sessionid ; ++s)
        {
                int idle;
        for (s = 1; s <= config->cluster_highest_sessionid ; ++s)
        {
                int idle;

-               if (!session[s].tunnel)
+               if (!session[s].opened)

                        continue;
 
                idle = time_now - session[s].last_packet;
                        continue;
 
                idle = time_now - session[s].last_packet;


@@ -4689,7 +4718,7 @@ int cmd_show_hist_open(struct cli_def *cli, char *command, char **argv, int argc
        for (s = 1; s <= config->cluster_highest_sessionid ; ++s)
        {
                int open = 0, d;
        for (s = 1; s <= config->cluster_highest_sessionid ; ++s)
        {
                int open = 0, d;

-               if (!session[s].tunnel)
+               if (!session[s].opened)

                        continue;
 
                d = time_now - session[s].opened;
                        continue;
 
                d = time_now - session[s].opened;


@@ -4716,75 +4745,45 @@ int cmd_show_hist_open(struct cli_def *cli, char *command, char **argv, int argc
 
 /* Unhide an avp.
  *
 
 /* Unhide an avp.
  *

- * This unencodes the AVP using the L2TP CHAP secret and the
- * previously stored random vector. It replaces the hidden data with
- * the cleartext data and returns the length of the cleartext data
- * (including the AVP "header" of 6 bytes).
- *
- * Based on code from rp-l2tpd by Roaring Penguin Software Inc.
+ * This unencodes the AVP using the L2TP secret and the previously
+ * stored random vector.  It overwrites the hidden data with the
+ * unhidden AVP subformat.

  */
  */

-static int unhide_avp(uint8_t *avp, tunnelidt t, sessionidt s, uint16_t length)
+static void unhide_value(uint8_t *value, size_t len, uint16_t type, uint8_t *vector, size_t vec_len)

 {
        MD5_CTX ctx;
 {
        MD5_CTX ctx;

-       uint8_t *cursor;

        uint8_t digest[16];
        uint8_t digest[16];

-       uint8_t working_vector[16];
-       uint16_t hidden_length;
-       uint8_t type[2];
-       size_t done, todo;
-       uint8_t *output;
-
-       // Find the AVP type.
-       type[0] = *(avp + 4);
-       type[1] = *(avp + 5);
-
-       // Line up with the hidden data
-       cursor = output = avp + 6;
+       uint8_t *last;
+       size_t d = 0;

 
        // Compute initial pad
        MD5Init(&ctx);
 
        // Compute initial pad
        MD5Init(&ctx);

-       MD5Update(&ctx, type, 2);
+       MD5Update(&ctx, (uint8_t) (type >> 8) & 0xff, 1);
+       MD5Update(&ctx, (uint8_t)  type       & 0xff, 1);

        MD5Update(&ctx, config->l2tpsecret, strlen(config->l2tpsecret));
        MD5Update(&ctx, config->l2tpsecret, strlen(config->l2tpsecret));

-       MD5Update(&ctx, session[s].random_vector, session[s].random_vector_length);
+       MD5Update(&ctx, vector, vec_len);

        MD5Final(digest, &ctx);
 
        MD5Final(digest, &ctx);
 

-       // Get hidden length
-       hidden_length = ((uint16_t) (digest[0] ^ cursor[0])) * 256 + (uint16_t) (digest[1] ^ cursor[1]);
+       // pointer to last decoded 16 octets
+       last = value;

 
 

-       // Keep these for later use
-       working_vector[0] = *cursor;
-       working_vector[1] = *(cursor + 1);
-       cursor += 2;
-
-       if (hidden_length > length - 8)
-       {
-               LOG(1, s, t, "Hidden length %d too long in AVP of length %d\n", (int) hidden_length, (int) length);
-               return 0;
-       }
-
-       /* Decrypt remainder */
-       done = 2;
-       todo = hidden_length;
-       while (todo)
+       while (len > 0)

        {
        {

-               working_vector[done] = *cursor;
-               *output = digest[done] ^ *cursor;
-               ++output;
-               ++cursor;
-               --todo;
-               ++done;
-               if (done == 16 && todo)
+               // calculate a new pad based on the last decoded block
+               if (d >= sizeof(digest))

                {
                {

-                       // Compute new digest
-                       done = 0;

                        MD5Init(&ctx);
                        MD5Update(&ctx, config->l2tpsecret, strlen(config->l2tpsecret));
                        MD5Init(&ctx);
                        MD5Update(&ctx, config->l2tpsecret, strlen(config->l2tpsecret));

-                       MD5Update(&ctx, &working_vector, 16);
+                       MD5Update(&ctx, last, sizeof(digest));

                        MD5Final(digest, &ctx);
                        MD5Final(digest, &ctx);

+
+                       d = 0;
+                       last = value;

                }
                }

-       }

 
 

-       return hidden_length + 6;
+               *value++ ^= digest[d++];
+               len--;
+       }

 }
 
 static int ip_filter_port(ip_filter_portt *p, uint16_t port)
 }
 
 static int ip_filter_port(ip_filter_portt *p, uint16_t port)